Update:
An explanation of what might have actually happened:
...today, international conferences are attended by Iran's President, not the Supreme Leader. So the person whom Mr Natwar Singh met at the NAM summit was probably the President, who at the time was Ali Khamenei. Perhaps his 1982 anecdote also refers to Ayatollah Khamenei (who was the president throughout the 1980s). He was not the supreme leader then, but he was an important man;
...